The present invention relates to an adsorbent suitable for selectively adsorbing or separating CO by a PSA (pressure swing adsorption) method, and a method of manufacturing the same.
Japanese Patent Disclosure (Kokai) No. 58-156517 discloses a solid adsorbent containing copper halide(I) and active carbon as a CO adsorbent. However, stable use of this adsorbent for a long period of time has never been reported. U.S. Pat. No. 4,019,879 describes an adsorbent prepared by carrying Cu(I) in zeolite whose silica/alumina ratio is as high as 20 to 200. In zeolite having such a high silica/alumina ratio, it is known that the number of cations capable of ion exchange tends to be reduced. It may be concluded that the CO adsorption amount per unit weight is reduced.
A CO desorption technique by the PSA method has been developed as a typical adsorption method. For example, Japanese Patent Disclosure (Kokai) No. 59-22625 describes a two-step treatment for performing a PSA to eliminate moisture and CO.sub.2 in a pretreatment step. Japanese Patent Disclosure (Kokai) No. 59-26121 describes a two-step treatment of separating CO from a converter gas. According to this method, mordenite is used as an adsorbent, and CO.sub.2 -PSA and CO-PSA are separately performed. These conventional proposals indicate that the adsorbents have a large CO adsorption amount near room temperature. However, the CO.sub.2 adsorption amount is larger than the CO adsorption amount. In order to separate CO from a gas mixture containing CO.sub.2, CO.sub.2 is separated from the gas mixture in the pretreatment, and then CO is separated by the CO-PSA process.